US3898840A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-frequency ultrasonic search unit
Assignee: STAVELEY INSTRUMENTS Inc 421 NORTH QUAY STREET KENNEWICK WA 99336 A CORP OF WA
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Filing: 1974-01-30
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Granted: 1975-08-12
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Expires: 1994-01-30
Abstract
Abstract A multi-frequency ultrasonic nondestructive testing system and a multi-frequency search unit for use in such a system are disclosed herein. The search unit includes a plurality of piezoelectric transducers for transmitting and receiving ultrasonic energy at a corresponding number of different frequencies. One transducer is adapted to transmit and/or receive relatively high frequency ultrasonic energy for resolving discontinuities on or near the surface of a workpiece while another transducer is provided to transmit and/or receive relatively low frequency ultrasonic energy for resolving discontinuities buried deep within the workpiece material.
Inventors
- 👤 Jerry T Mcelroy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:10
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/34; G01N29/348; B; B06; B06B; B06B1/00; B06B1/02; B06B1/06; B06B1/0644; B06B1/0662; B06B1/0681; G01N29/04; G01N29/06; G01N29/0609
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
219 words
In a nondestructive testing system for inspecting a workpiece with a dual transducer search unit in which a first frequency electrical channel is connected to one of the search unit transducers and a second frequency electrical channel is connected to the other search unit transducer for respective transmission and/or reception of ultrasonic energy at different frequencies, said search unit including: an inner transducer having a piezoelectric disc element with front and rear faces and electrode means affixed thereto; an outer transducer having an annular piezoelectric element with front and rear faces mounted coaxially with respect to said inner transducer disc element and having electrode means affixed thereto; an acoustical insulating structure disposed coaxially between said inner and outer transducers to minimize the transfer of acoustical energy radially between said transducers; and inner and outer acoustical transmitting means coupled to the front faces of said transducer elements for transmitting ultrasonic energy between said transducers and a forward working portion of said search unit, at least one of said inner and outer transmitting means including acoustical modifying means for differentially modifying acoustical waves associated with one of said transducers relative to the other transducer, whereby optimum transfer of ultrasonic energy to and from the workpiece may be achieved in accordance with the different frequencies associated with the inner and outer transducers.
Claim 2
Dependent Claim
219 words
In a nondestructive testing system for inspecting a workpiece with a dual transducer search unit in which a first frequency electrical channel is connected to one of the search unit transducers and a second frequency electrical channel is connected to the other search unit transducer for respective transmission and/or reception of ultrasonic energy at different frequencies, said search unit including: an inner transducer having a piezoelectric disc element with front and rear faces and electrode means affixed thereto; an outer transducer having an annular piezoelectric element with front and rear faces mounted coaxially with respect to said inner transducer disc element and having electrode means affixed thereto; an acoustical insulating structure disposed coaxially between said inner and outer transducers to minimize the transfer of acoustical energy radially between said transducers; and inner and outer acoustical transmitting means coupled to the front faces of said transducer elements for transmitting ultrasonic energy between said transducers and a forward working portion of said search unit, at least one of said inner and outer transmitting means including acoustical modifying means for differentially modifying acoustical waves associated with one of said transducers relative to the other transducer, whereby optimum transfer of ultrasonic energy to and from the workpiece may be achieved in accordance with the different frequencies associated with the inner and outer transducers.
Claim 3
Dependent Claim
138 words
In the nondestructive testing system of claim 1 wherein said first frequency electrical channel Is of a relatively high frequency and is connected to said inner transducer to test for discontinuities at the surface and in the near surface zone of the workpiece while the second frequency electrical channel is connected to said outer transducer and is of a relatively low frequency to test for discontinuities beyond the near surface zone of the workpiece, and said inner acoustical transmitting means including a delay medium as said modifying means for differentially delaying ultrasonic waves associated with said inner transducer relative to waves associated with said outer transducer, whereby a built-in time delay is provided between the pulsing of said inner transducer and the reception thereby of reflected ultrasonic energy from the surface and near surface zone of the workpiece.
Claim 4
Dependent Claim
121 words
In the nondestructive testing system of claim 1, the first frequency electrical channel providing a relatively higher frequency and being connected to said inner transducer for resolving discontinuities located at the surface and within the near surface zone of a workpiece, the second frequency electrical channel being of a relatively lower frequency and connected to said outer transducer for resolving discontinuities beyond the near surface zone of the workpiece, and said inner and outer acoustical transmitting means including acoustical focusing lenses for focusing ultrasonic energy associated with said inner transducer at the surface and near surface zone of a workpiece and for focusing ultrasonic energy associated with said outer transducer at a region beyond the near surface zone of such workpiece.
Claim 5
Dependent Claim
69 words
In the nondestructive testing system of claim 1 wherein said search unit is adapted to test workpieces while immersed therewith in a liquid bath, and said inner and outer transmitting means associated with said inner and outer transducers respectively include curvilinear focusing structures providing said modifying means in which ultrasonic energy transmitted to and from said inner and outer transducers is differentially focused to different depths of the workpiece.
Claim 6
Dependent Claim
35 words
In the nondestructive testing system of claim 1, said inner and outer transducers being radially spaced apart, and said acoustical insulating structure including a sound absorbent material disposed in the radial space between said transducers.
Claim 7
Dependent Claim
46 words
In the testing system of claim 5, said inner and outer transducers including acoustical dampening structures affixed to the rear faces thereof and extending rearwardly thereof, said sound absorbent material defining a generally hollow cylindrical structure extending coaxially between and axially coextensive with said dampening structures.
Claim 8
Dependent Claim
95 words
In the nondestructive testing system of claim 5, said search unit including inner and outer dampening structures affixed to the rear faces of said inner and outer transducers for dissipating ultrasonic energy transmitted rearwardly of said transducers, at least one of said dampening structures including a sloping rear surface remote from the rear face of the associated transducer to enhance the dissipation of rearwardly transmitted ultrasonic energy, and said acoustical insulating structure further defined by said sound absorbent material being cast to form a generally hollow cylindrical structure substantially axially coextensive with said dampening structures.
Claim 9
Dependent Claim
44 words
In the nondestructive testing system of claim 1, said piezoelectric elements of said inner and outer transducers selected to have different thicknesses according to the different frequencies associated therewith and said inner and outer transducers being physically, electrically and acoustically isolated from each other.
Claim 10
Dependent Claim
52 words
In the nondestructive testing system of claim 1, said inner and outer transducers being dimensioned to define a radial space between the outer circumference of said inner transducer and the inner circumference of said outer annular transducer, and said acoustical insulating structure including a cast acoustical shield formed in said radial spacE.
Claim 11
Dependent Claim
43 words
In the nondestructive testing system of claim 1, at least one of said inner and outer acoustical transmitting means including a contoured sound transmitting structure for focusing ultrasonic energy to and from the associated transducer at a selected depth zone of the workpiece.
Claim 12
Dependent Claim
157 words
An ultrasonic nondestructive search unit for inspecting a workpiece in a system having a first frequency electrical channel and a second frequency electrical channel, said search unit including: an inner transducer having a piezoelectric disc element with front and rear faces and electrode means affixed thereto, said electrode means being adapted to be connected to said first frequency electrical channel; an outer transducer having an annular piezoelectric element with front and rear faces mounted coaxially with respect to said inner transducer disc element and having electrode means affixed thereto and being adapted for connection to said second frequency electrical channel; an acoustical insulating structure disposed coaxially between said inner and outer tranducers to minimize the transfer of acoustical energy therebetween; and inner and outer acoustical transmitting means coupled to the front faces of said transducer elements for optimum transfer of ultrasonic energy between said transducers and a workpiece at the particular frequency associated with each such transducer.
Claim 13
Dependent Claim
157 words
An ultrasonic nondestructive search unit for inspecting a workpiece in a system having a first frequency electrical channel and a second frequency electrical channel, said search unit including: an inner transducer having a piezoelectric disc element with front and rear faces and electrode means affixed thereto, said electrode means being adapted to be connected to said first frequency electrical channel; an outer transducer having an annular piezoelectric element with front and rear faces mounted coaxially with respect to said inner transducer disc element and having electrode means affixed thereto and being adapted for connection to said second frequency electrical channel; an acoustical insulating structure disposed coaxially between said inner and outer tranducers to minimize the transfer of acoustical energy therebetween; and inner and outer acoustical transmitting means coupled to the front faces of said transducer elements for optimum transfer of ultrasonic energy between said transducers and a workpiece at the particular frequency associated with each such transducer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-11 | 1979-02-10 | 1979-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-11 | 1983-02-10 | 1983-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-11 | 1987-02-10 | 1987-08-12 | $7700.00 | Window Closed / Lapsed |